Method and apparatus for curving a catheter

ABSTRACT

An apparatus and method for curving a catheter after deployment include a catheter having a primary lumen, a secondary lumen, and a resilient fiber contained within the secondary lumen. The resilient fiber and the secondary lumen have corresponding, preformed curve shapes when the catheter is in a straight, unstressed condition. The resilient fiber is slidable within the secondary lumen to create a desired curve shape in the catheter as the curved portion of the resilient fiber slides into an originally straight portion of the secondary lumen. In another embodiment, the preformed curve shape of the resilient fiber is held in a straight condition within a stiff, marker ring segment of the catheter until after the catheter is deployed. Once deployed, the resilient fiber is slid out of the marker ring segment, and the preformed curve shape of the resilient fiber creates a corresponding curve shape in the catheter.

RELATED APPLICATIONS

This application is a continuation of application Ser. No. 10/877,424filed on Jun. 25, 2004, now U.S. Pat. No. 8,007,489 which claims thebenefit of the Applicant's provisional patent Application No. 60/483,867filed on Jun. 25, 2003, and also relates to the subject matter ofApplicant's copending U.S. application Ser. No. 10/167,718 filed on Jun.11, 2002. All of these related applications are hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to catheters and, in particular,to catheters that can be curved or bent at their distal ends or otherselected locations, and methods for making and deploying such catheters.

2. Description of the Related Art

Catheters frequently have “preset” curves in them to enhance thephysician's ability to introduce the catheter to the desired location.Usually, this curve is “set” in the catheter by first bending thecatheter to the desired shape, then applying heat to the catheter whilein this curved state, and then allowing the catheter to cool while stillin this curved shape. The plastic memory of the polymer allows thecurved shape to be maintained after cooling. In some cases, the cathetercan be curved without heat by cold working the catheter into a curvedshape.

The existing methods of curving catheters suffer from a number ofdisadvantages. First, the curved shape requires some rigidity of thecatheter to maintain the curvature. Second, the curve can only be “set”outside of the body. Third, the soft wall of the catheter needed to makethe curve shape often becomes crushed or kinked during use. Fourth, asmall size and tight curvature of the catheter is difficult to achieve.

Thus, there is a need in the industry for an improved method andapparatus for making and deploying catheters that allow the catheter tobe curved or bent at its distal end or other selected locations duringdeployment.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method andapparatus for curving a distal end of a catheter that overcomes theproblems in the above-mentioned prior art.

It is a further object of the present invention to provide an improvedmethod for introducing curves into catheters while the catheters remaininside the body.

It is a further object of the present invention to provide a small neurovascular catheter having a deflectable tip that allows improvedpositioning within the vascular system for transmitting subsequentdiagnostic and therapeutic devices or media.

It is a further object of the present invention to provide an improvedmethod for introducing a curve in a catheter that uses a marker bandsection at the distal tip of the catheter in conjunction with aprecurved distal segment of a resilient filament to create the desiredcurve in the catheter.

To achieve the foregoing and other objects and in accordance with thepurpose of the present invention, as embodied and broadly describedherein, a first embodiment of the present invention provides anapparatus and method for curving a catheter having a primary lumen, asecondary lumen, and a resilient fiber contained within the secondarylumen. A portion of the secondary lumen near the distal end of thecatheter is nonparallel to the primary lumen and may form, for example,a partial loop configuration relative to the primary lumen. Theresilient fiber and the secondary lumen have corresponding, preformedcurve shapes when the catheter is in a straight, unstressed condition.The resilient fiber is slidable within the secondary lumen to create adesired curve shape in the catheter as the curved portion of theresilient fiber slides into an originally straight portion of thesecondary lumen.

In another embodiment, the resilient fiber is disposed within a channel,and the preformed curve shape of the resilient fiber is held in astraight condition within a stiff, marker ring segment of the catheteruntil after the catheter is deployed within a patient's body. Oncedeployed, the resilient fiber is slid out of the stiff, marker ringsegment, and the resilient fiber regains its preformed curve shape andcreates a corresponding curve shape in a soft, flexible portion of thecatheter adjacent to the marker ring segment. A second channel and asecond resilient fiber can be used to temporarily straighten thecatheter to adjust its position within the patient's body.

Additional objects, advantages, and novel features of the invention willbe set forth in the following description, and will become apparent tothose skilled in the art upon reading this description or practicing theinvention. The objects and advantages of the invention may be realizedand attained by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more clearly appreciated as thedisclosure of the present invention is made with reference to theaccompanying drawings. In the drawings:

FIG. 1 is a side view of resilient fiber core having a preset curvaturenear a distal end for use in the present invention.

FIG. 2 is a side view of a catheter according to a first embodiment ofthe present invention, which includes a primary lumen, an additionallumen attached to the primary lumen, and the resilient fiber core ofFIG. 1 contained within the additional lumen in an unstressed state.

FIG. 3 is a side view of the catheter shown in FIG. 2 with the cathetertip being deflected by sliding the resilient fiber core within theadditional lumen.

FIG. 4 is a side view of a catheter according to a variation of thefirst embodiment of the present invention in which the additional lumenis contained within the wall of the primary lumen.

FIG. 5 is a perspective view of a catheter having a marker band locatedat the distal end of the catheter for visualization during deployment.

FIG. 6 is a perspective view of a catheter according to a secondembodiment of the present invention in which a marker band is located atthe distal end of the catheter, and a channel is provided in the wall ofthe catheter for receiving a resilient fiber core.

FIG. 7 is a cross section side view of the catheter shown in FIG. 6 witha resilient fiber core having a precurved distal segment being pulledinto the channel in the wall of the catheter.

FIG. 8 is a cross section view of the catheter shown in FIG. 7 with theresilient fiber core positioned with its precurved distal segmentcontained within the stiffened segment of the catheter provided by themarker band.

FIG. 9 is a cross section view of the catheter shown in FIG. 7 with theprecurved distal segment of the resilient fiber core being pulled intothe soft section of the catheter proximal the marker band.

FIG. 10 is perspective view of a modified catheter according to a secondembodiment of the present invention in which a second channel isprovided in the wall of the catheter for receiving a second resilientfiber for fine tuning the catheter's position within the body.

DETAILED DESCRIPTION OF THE INVENTION

Methods and apparatus for curving a distal end of a catheter accordingto the present invention will be described in detail hereinafter withreference to FIGS. 1 to 10 of the accompanying drawings.

A catheter 10 having a deflectable distal tip 11 according to a firstembodiment of the present invention will be described with reference toFIGS. 1 to 4 of the drawings. The catheter 10 includes a primary lumen12 as in conventional catheters, and a secondary lumen 13 that is eitherattached to the primary lumen 12 (as shown in FIGS. 2 and 3) orcontained within the wall of the primary lumen 12 (as shown in FIG. 4).The secondary lumen 13 transverses the primary lumen 12 from theproximal end 14 of the catheter 10 to near the distal end 11 where itforms a partial loop configuration 15 (e.g., 180 degrees as shown inFIG. 2) and begins to track back toward the proximal end 14 of thecatheter 10. Other shapes for the curved portion 15 of the secondarylumen 13 can also be used as long as the secondary lumen 13 has at leasta portion near its distal end that is nonparallel to the primary lumen12; i.e., the distal end of the secondary lumen 13 is curved, bent, orotherwise divergent from a path parallel to the primary lumen 12.

A small diameter, resilient fiber 16 is inserted within the secondarylumen 13. For example, the resilient fiber 16 can be formed of ametallic steel heat-tempered spring alloy, such as atitanium-nickel-chromium alloy, or a boron fiber having a diameter of0.001 to 0.006 inches. The resilient fiber 16 has an unstressed shapethat corresponds to the unstressed shape of the secondary lumen 13, asshown in FIG. 1. The catheter 10 shown in FIG. 2 has the resilient fiber16 inserted within the secondary lumen 13 and an overall shape which issubstantially straight when the resilient fiber 16 and the secondarylumen 13 are in their unstressed states.

The catheter 10 of the present invention is preferably formed of anylon, urethane, PE, TFE, or other suitable polymer material which isvery soft and offers little resistance to the preformed shape of theresilient fiber 16. The catheter 10 can be formed, for example, usingthe nonextrusion manufacturing method and apparatus described inApplicant's U.S. Pat. No. 6,030,371. Using this method, the catheter 10can be formed with a variable hardness over its length by continuouslychanging the constituents or mixtures of the polymer material(s) beingused. The catheter can thus have a relatively stiff or hard portion nearits proximal end 14 and a relatively softer portion near its distal end11.

When deflection at the distal tip 11 of the catheter 10 is desired, theresilient fiber 16 is pulled at its proximal end 17 and the curved part18 of the resilient fiber 16 slides into the straight portion 19 of thesecondary lumen 13. As the resilient fiber 16 slides within the straightportion 19 of the secondary lumen 13, that portion of the secondarylumen 13 will begin to take the shape of the curved part 18 of theresilient fiber 16, resulting in a deflected catheter tip 11 as shown inFIG. 3.

The secondary lumen 13 and the resilient fiber 16 are not limited to a180-degree bend or a single bend, as shown in FIGS. 1 and 2. Instead,multiple bends or bends of different angles in the secondary lumen 13and the resilient fiber 16 can be used to deflect the catheter 10 in aspecific way for a given application or procedure.

The deflectable tip 11 of the catheter 10 according to the firstembodiment allows the catheter 10 to remain straight while traversingthe vascular system to the desired location within the anatomy. Thecatheter 10 can then be deflected at a specific angle near the distaltip 11, so that the catheter 10 can be better positioned fortransmitting subsequent diagnostic and therapeutic devices or media.

A catheter 20 according to a second embodiment of the present inventionwill now be described with reference to FIGS. 5 to 10 of the drawings. Aconventional catheter 20 c having a marker band 21 at its distal end 22is shown in FIG. 5. The marker band 21 is typically provided forvisualization to facilitate positioning the distal end 22 of thecatheter 20 c within the anatomy.

The catheter 20 according to the second embodiment is shown in FIGS. 6to 9. The catheter 20 has a marker band 23 at its distal end 24, whichcan be used for visualization similar to the marker band 21 in theconventional catheter 20 c of FIG. 5. The marker band 23 is formed of ahard polymer, while the other part 25 near the distal end of thecatheter 20 is formed of a soft, flexible polymer material. The markerband 23 does not affect the overall flexibility of the catheter 20because it only affects the catheter shaft for a very short region(i.e., the catheter 20 is stiff only where the marker band 23 islocated).

The catheter 20 has a primary lumen 26 and a channel 27 formed in thewall of the primary lumen 26. A resilient fiber 28 having a precurveddistal segment 29 is inserted into the channel 27 and pulled into thecatheter 20 as shown in FIG. 7. The precurved segment 29 of theresilient fiber 28 is straightened when it is pulled into the catheter20, as shown in FIG. 8. The now straightened segment 29 of the resilientfiber 28 is short enough that it can be contained within the section ofthe channel 27 that lies within the stiffened section of the catheter 20formed by the marker band 23. Since the catheter 20 is stiff in thissection as a result of the hard polymer used to create the marker band23, the resilient filament 28 will be maintained in a straightenedorientation while it resides within this section of the catheter 20. Thecatheter 20 can then be easily navigated into the body.

Once the catheter 20 is navigated into position, the resilient fiber 28can be pulled back so that the precurved portion 29 of the resilientfiber 28 is pulled into the soft section 25 of the catheter 20 justproximal the hard section 23. Once this occurs, the resilient fiber 28will overcome the bending resistance of the soft section 25 and willimpart a curve to the catheter 20 as shown in FIG. 9. Once the procedureis completed, the resilient fiber 28 is pulled out and the now straightcatheter 20 is easily removed.

A second channel 30, as shown in FIG. 10, can be provided in thecatheter 20 adjacent to the first channel 27. A second resilient fiber(not shown) can then be slid into the second channel 30 after the curveis imparted to the catheter 20 by the first resilient fiber 28. Thesecond resilient fiber can be used to temporarily straighten thecatheter 20 to “fine tune” its position in the body.

The catheters 10 and 20 described above according to the first andsecond embodiments of the invention will be extremely useful inneurovascular applications where it is necessary to insert a straightcatheter to the site and then introduce a curve after the catheterreaches the site.

While the invention has been specifically described in connection withspecific embodiments thereof, it is to be understood that this is by wayof illustration and not of limitation, and the scope of the appendedclaims should be construed as broadly as the prior art will permit.

1. A method for curving a catheter, comprising: providing a resilientfiber with a preformed curve shape in a portion thereof; providing acatheter having a first channel, a hard polymer ring that creates astiffened section extending along a distal portion of the catheter, anda soft section proximal of the stiffened section which has a lowerbending resistance than the stiffened section; inserting the resilientfiber into the first channel of the catheter with the preformed portionof the resilient fiber contained substantially within a length of thestiffened section of the catheter created by the hard polymer ring withthe preformed portion of the resilient fiber maintained in astraightened orientation within said stiffened section; deploying thecatheter to a desired location within a body; and pulling the resilientfiber in a proximal direction within the first channel until at leastpart of the preformed portion of the resilient fiber slides out of thestiffened section created by the hard polymer ring and into the softsection and thereby imparts a curve shape to the catheter.
 2. A catheterthat can be deployed with a curved shape, comprising: a first channel, ahard polymer ring that creates a stiffened section extending alone adistal portion of the catheter, and a soft section proximal of thestiffened section which has a lower bending resistance than thestiffened section; a resilient fiber with a preformed curve shape in aportion thereof, said fiber being disposed within the first channel andslidable therein between a first position in which the preformed portionof the resilient fiber is contained substantially within a length of thestiffened section of the catheter created by the hard polymer ring andis maintained in a straightened orientation within said stiffenedsection, and a second position in which at least part of the preformedportion of the resilient fiber is pulled in a proximal direction out ofthe stiffened section created by the hard polymer ring and into the softsection and thereby imparts a curve shape to the catheter.
 3. Thecatheter according to claim 2, wherein the hard polymer ring is formedof a hard polymer material, and the soft section of the catheteradjacent to the stiffened section created by the hard polymer ring isformed of a relatively soft, flexible polymer material.